We may receive a commission on purchases made from links. Whenever I get my hands on a newly bought used car, my checklist includes inspecting a few underhood items as part of the "getting-to-know-the ...

Symptom: An engine’s cooling system is overheating. The coolant level is low, but there are no visible leaks and no water in the engine crankcase to hint of water jacket or cylinder head problems.

Cooling systems are pressurized, and the radiator cap is there to manage the pressure. Downflow radiators can only have the cap on the hot side (where hot coolant exits the engine), so this is the ...